The objectives of this proposal are to determine the biochemical mechanisms involved in the epididymal maturation of mammalian sperm. This process results in the conversion of sperm with limited fertilization potential into cells which are fully competent to fertilize an ovum. Since spermatozoa are terminally differentiated cells, possessing limited biosynthetic capabilities, it would appear that the interaction of the cells with their environment, i.e. epididymal fluid, may play the major role in the development of a fully competent cell. A two step approach for the study of epididymal development is being proposed. First a combination of biochemical and immunological techniques will be used to determine: (i) what changes have occurred to the plasma membrane during epididymal migration and (ii) whether such alterations are a consequence of the interaction of sperm with epididymal fluid. Second, experiments will be conducted in the general area of cyclic nucleotide metabolism. Specifically, we will determine (1) how cAMP levels are regulated in sperm; (ii) what role cAMP-dependent protein kinases play in sperm metabolism and (iii) since Ca2+ is an essential component of the acrosomal reactions, what processes in sperm are regulated in a Ca2+/calmodulin-dependent manner. The long term goal of this project will be to determine whether there is a correlation between alterations in plasma membrane structure and changes in cyclic nucleotide metabolism in sperm.